Multivariate restricted maximum likelihood estimation of genetic parameters for production traits in three selected turkey strains

Abstract

Summary -Genetic parameters related to growth, carcass composition and egg production were estimated on three (two female and one male) commercial strains of turkey using the method of restricted maximum likelihood (R.EML). In order to account for the sexual dimorphism in turkeys, body weight (BW, measured at 12 and 16 weeks of age) was considered as a sex-limited trait. As many as seven traits were analyzed simultaneously in one strain. Egg numbers were normalized using a Box-Cox transformation. Three different genetic models were used. The

Genetic analysis on body weight at different ages in broiler chicken raised in commercial environment

“…Inclusion of both the maternal effects in the model improved considerably the fit of models for BW traits at weeks 0, 8 and 12 in dual‐purpose chicken compared to the models without or with only one of the maternal effects (Jasouri et al, ). A similar conclusion on the inclusion of both the maternal effects in the model was for BW at weeks 0 and 5 in broilers (Maniatis et al, ), BW at week 8 in Iranian native chicken (Zonuz et al, ), BW at weeks 12 and 16 in turkeys (Chapuis et al, ) and juvenile BW in broilers (Koerhuis & Thompson, ). These five studies used REML for estimation of variance components, and comparison criteria between models were based on log‐likelihood, Akaike information criterion (AIC) and Bayesian information criterion (BIC).…”

“…Indications of sex‐by‐genotype interaction can be heterogeneous variances, different heritability and correlation of less than one between male and female BWs. Sex‐by‐genotype interaction for BW has been demonstrated in broilers (van der Heide et al, ; Mebratie et al, ) and other poultry species (Chapuis et al, ; Mignon‐Grasteau, Beaumont, Poivey, & De Rochambeau, ). These studies show that variances between sexes could differ by a factor of 2 or more.…”

“…In our studies, the maternal additive genetic effect was not included in the multivariate model (3) as the effect was not significant for all BW traits except male BW1 (Appendix 3). Meanwhile, many studies show that the presence of the maternal effects including both additive genetic and permanent environmental effects can increase the fit of the models (Chapuis, Tixier‐Boichard, Delabrosse, & Ducrocq, ; Jasouri et al, ; Koerhuis & Thompson, ; Maniatis et al, ; Zonuz et al, ). Inclusion of both the maternal effects in the model improved considerably the fit of models for BW traits at weeks 0, 8 and 12 in dual‐purpose chicken compared to the models without or with only one of the maternal effects (Jasouri et al, ).…”